Major research emphasis again this year will center on the toxic stress metabolites produced by the Sweetpotato (Ipomoea batatas) in response to fungus infection and other injurious stimuli. Principal concern will be directed toward the mechanism of pulmonary toxicity exhibited by 4-ipomeanol. This will conclude additional studies on aspects of its activation by cytochrome dependent-mixed function oxygenase system and the covalent binding to subcellular material. Also, studies will be made of the histopathological features of the resultant lung damage as revealed by electron microscopy. Various aspects of the biosynthetic routes for both hepatotoxic and lung-toxic metabolites will continue to be studied, including the respective roles of the stimulatory fungus and the host plant. Enzyme systems responsible for interconversions among metabolites will be isolated and characterized. Work on the development of quantitative analytical methods for the pulmonary toxins will continue, and if successful procedures are devised, they will be used in measurement of toxin levels in marketed sweetpotatoes. In the area of mycotoxins, efforts will be made to define the toxic principle of corn infected with Fusarium moniliforme that causes leukoencephalomalacia in equine animals. Specifically, the recently discovered metabolite known as "moniliformin" will be synthesized and administered to horses or donkeys in order to ascertain any possible relationship of this substance to the encephalomalacia. The tremorgenic toxin of P. crustosum, called Penitrem A, will receive attention with respect to its central nervous system toxicity and the biochemical mechanism of hormone stimulation in rats.